Hi Loris, thanks for the question and congratulations on your new role at the Zig Software Foundation. We originally planned on supporting Zig in Japan via support contracts and this is from that preparation. Trademarks have multiple categories and one such category is for contract work and related materials. We don't plan to use this trademark to harm Zig.
since you have instead settled on forking as the zen PL, which is your right to do, would you turn that trademark over to the zig foundation as a show of good faith?
I find this hard to believe. There are plenty of companies out there providing some kind of product built on top of another (e.g. a language), without registering the name of said product as a trademark of their own.
To me it sounds more like you didn't get the things you wanted, and instead decided to try and take them by force.